Mouth ulcers are sores or open lesions in the mouth. (See also mouth sores or canker sores)

Mouth ulcers are caused by many disorders. These include:

• Canker sores
• Gingivostomatitis
• Herpes simplex
• Leukoplakia
• Oral cancer
• Oral lichen planus
• Oral thrush

The skin lesion of histoplasmosis may also appear as a mouth ulcer.

Canker sores are more common in young adults than in children or older adults.

• Open sores in the mouth
• Pain or discomfort in the mouth

The appearance and exact location of lesions varies with the specific disorder.

A health care provider or dentist usually diagnoses the type of mouth ulcer, based on its appearance and location. Blood tests or a biopsy of the ulcer may be needed to confirm the cause.

The goal of treatment is to relieve symptoms. The cause, if known, should be treated.

Gentle, thorough oral hygiene may relieve some of the symptoms. Topical (rubbed on) antihistamines, antacids, corticosteroids, or other soothing preparations may be recommended for applying directly to the ulcer.

Avoid hot or spicy foods, which often increase the pain of mouth ulcers.

The outcome varies depending on the cause of the ulcer. Many mouth ulcers are harmless ( benign)and heal without treatment. Sometimes, mouth cancer first appears as an ulcer that won't heal.

• Cellulitis of the mouth, from secondary bacterial infection of ulcers
• Dental infections (tooth abscesses)
• Oral cancer
• Spread of contagious disorders to other people

Call for an appointment with your health care provider if your mouth ulcers don't go away after 3 weeks. Call for an appointment with your health care provider if mouth ulcers return frequently, or if new symptoms develop.

Good oral hygiene may help prevent some types of mouth ulcers, as well as some complications from mouth ulcers. Good oral hygiene includes brushing the teeth at least twice per day, flossing at least daily, and getting regular professional dental cleanings and examinations.

Gonsalves WC, Chi AC, Neville BW. Common oral lesions: Part I. Superficial mucosal lesions. Am Fam Physician. 2007;75(4):501-507.

Gonsalves WC, Chi AC, Neville BW. Common oral lesions: Part II. Masses and neoplasia. Am Fam Physician. 2007;75(4):509-512.

Gonsalves WC, Wrightson AS, Henry RG. Common oral conditions in older persons. Am Fam Physician. 2008;78(7):845-852.